/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: syyyy
 * Date: 2025-07-17
 * Time: 13:03
 */
public class Test2 {
    public static String func(String s){
        int[] count=new int[256];
        StringBuilder stringBuilder=new StringBuilder();
        for (int i = 0; i < s.length(); i++) {
            char ch=s.charAt(i);
            count[ch]++;
            if(count[ch]==1){
                stringBuilder.append(ch);
            }
        }

        return stringBuilder.toString();
    }

    public static void main(String[] args) {
        String s="AbCaCb";
        String ret=func(s);
        System.out.println(ret);

    }
}
